# OneMapSGAPI R Package

The OneMapSGAPI package provides useful wrappers for the OneMapSG API client. It allows users to easily query spatial data from the API in a tidy format and provides additional functionalities to allow easy data manipulation.

    library(onemapsgapi)
    library(dplyr)
    #>
    #> Attaching package: 'dplyr'
    #> The following objects are masked from 'package:stats':
    #>
    #>     filter, lag
    #> The following objects are masked from 'package:base':
    #>
    #>     intersect, setdiff, setequal, union

## Search/ Geocode

This function is a wrapper for the Search API. It allows input of a dataframe of place names and output of the original dataframe with additional columns, including spatial coordinates and address information. Users can also optionally return the output an `sf` dataframe. If an error occurs, the result for that row will be empty and a warning message with the API error and status code will be printed.

Please note that only the top result returned by the API will be included.

    df <- tibble(
       places = c("a", "b", "c", "d"),
       address = c("raffles place mrt", "suntec city", "nus", "100353")
       )

    geocode_onemap(df, "address",
       return_geom=TRUE, address_details = TRUE, return_spatial = TRUE)

## Authentication

This function is a wrapper for the Authentication API endpoint In order to query data, most API endpoints in the OneMapSG API require a token. First-time users can register themselves using the OneMapSG registration form. Subsequently, they can retrieve their tokens using the `get_token()` function with their email and password, for example:

    token <- get_token("user@example.com", "password")

The function will also print a message informing users of the token’s expiry date and time.

## Themes

These functions are wrappers for the Themes API endpoints. Themes in the OneMap SG API refer to types of locations, such as kindergartens, parks, hawker centres etc.

### Check Theme Status

The `get_theme_status()` function allows users to check if data associated with a theme has been updated after a certain time. It returns a named logical.

    # returns named logical
    get_theme_status(token, "kindergartens")
    get_theme_status(token, "hotels", "2020-01-01", "12:00:00")

    # throws an error, along with the API error message and status code
    get_theme_status("invalid_token", "blood_bank")

    # throws an error, along with the API error message and status code
    get_theme_status(token, "invalid_theme")

### Get Theme Information

The `get_theme_info()` function allows users to get information related to a specific theme. It returns a named character vector with Theme Name and Query Name.

    # returns named character vector
    get_theme_status(token, "kindergartens")

If an error occurs, the function throws an error, along with the API error message and status code.

    # throws an error, along with the API error message and status code
    get_theme_status("invalid_token", "blood_bank")

    # throws an error, along with the API error message and status code
    get_theme_status(token, "invalid_theme")

### Find Themes of Interest

The `search_themes()` function allows users to find details of themes of interest. It returns a tibble of themes matching user’s search terms. Alternatively, if no search terms are added, a tibble of all themes available through the API is returned. The variable THEMENAME in the output tibble serves as the input for getting theme data.

    # return all themes related to "hdb" or "parks"
    search_themes(token, "hdb", "parks")

    # return all possible themes
    search_themes(token)

    # return all possible themes, with less variables
    search_themes(token, more_info = FALSE)

If an error occurs, the function throws an error, along with the API error message and status code.

    search_themes("my_invalid_token")

### Get Theme Data

The function `get_theme()` returns data related to a particular theme, often location coordinates and other information. It returns the output as a tibble, or prints a warning message when an error is encountered. All tibbles will contain the variables: NAME, DESCRIPTION, ADDRESSPOSTALCODE, ADDRESSSTREETNAME, Lat, Lng, ICON_NAME, and some provide additional information; for example, query hawker centres gives additional information about the completion date of each hawker centre. Option to return a spatial dataframe available.

    # return all hotel data
    get_theme(token, "hotels")

    # return all monuments data within a bounding area
    get_theme(token, "monuments", extents = "1.291789,%20103.7796402,1.3290461,%20103.8726032")

    # return all monuments data as a sf dataframe
    get_theme(token, "monuments", return_spatial = TRUE)

    # returns a list of status tibble and output tibble
    get_theme(token, "funeralparlours", return_info = TRUE) |>
      str()

    # error: throws an error, along with the API error message and status code
    get_theme("invalid_token", "hotels")

    # error: throws an error, along with the API error message and status code
    get_theme(token, "non-existent-theme")

    # error: output is query_info, warning message query did not return any records
    get_theme(token, "ura_parking_lot", "1.291789,%20103.7796402,1.3290461,%20103.8726032")

## Planning Areas

These functions are a wrapper for the Planning Area API. Planning Area API endpoints allow users to get spatial data and data related to the planning areas in Singapore. This package provides users with the ability to query the data and optionally handles necessary spatial data wrangling on behalf of the user.

### Get Planning Areas

The function `get_planning_areas()` allows users to query all the spatial polygons associated with Singapore’s planning areas, for certain years. The function also optionally helps users transform raw geojson strings into `sf` objects.

If the parameter `return_spatial = FALSE`, the function returns a raw JSON object with planning names and geojson string vectors.

    # returns raw JSON object
    get_planning_areas(token)
    get_planning_areas(token, 2008)

If the parameter `return_spatial = TRUE`, any missing geojson objects will be dropped (this affects the “Others” planning area returned by the API). The returned outputs are NOT projected.

    # returns dataframe of class "sf"
    get_planning_areas(token, return_spatial = TRUE)

Note that if the user specifies to return_spatial but does not have the sf package installed, the function will return the raw JSON and print a warning message.

If an error occurs, the function throws an error, along with the API error message and status code.

    # error: output is NULL, warning message shows status code
    get_planning_areas("invalid_token")

### Get Planning Area Names

The function `get_planning_names()` allows users to query all planning area names for certain years. The function returns a tibble with planning area code and planning area name.

    # returns tibble
    get_planning_names(token)
    get_planning_names(token, 2008)

If an error occurs, the function throws an error, along with the API error message and status code.

    # error: throws an error, along with the API error message and status code
    get_planning_names("invalid_token")

### Get Planning Area Polygon

The function `get_planning_polygon()` allows users to query a particular planning area polygon containing the specified location point. The function also optionally helps users transform raw geojson string output into an `sf` object.

If the parameter `return_spatial = FALSE`, the function returns a raw JSON object with planning names and geojson string vectors.

    # returns raw JSON object
    get_planning_polygon(token, lat = 1.429443081, lon = 103.835005)
    get_planning_polygon(token, lat = 1.429443081, lon = 103.835005, year = 2008)

If the parameter `return_spatial = TRUE`, any missing geojson objects will be dropped (this affects the “Others” planning area returned by the API). The returned outputs are NOT projected.

    # returns dataframe of class "sf"
    get_planning_polygon(token, lat = 1.429443081, lon = 103.835005, return_spatial = TRUE)

Note that if the user specifies a read method but does not have the corresponding package installed, the function will return the raw JSON and print a warning message.

If an error occurs, the function throws an error, along with the API error message and status code.

    # error & will not run: missing lat and lon arguments
    get_planning_polygon("invalid_token")
    # error: throws an error, along with the API error message and status code
    get_planning_polygon(token, "invalidlat", "invalidlon")

## Population Query

These functions are a wrapper for the Population Query API. Population Query API endpoints allow users to pull socio-economic datasets by planning area, which each endpoint representing a dataset (e.g. `getPopulationAgeGroup` provides age group summary statistics by planning area). This package combines querying different Popquery API endpoints into single functions.

### Multiple Queries

The function `get_pop_queries()` allows users to query multiple datasets for multiple towns, years and genders.

The `gender` parameter is only valid for the getEconomicStatus, getEthnicGroup, getMaritalStatus and getPopulationAgeGroup endpoints. If specified for other endpoints, the parameter will be dropped.

If gender is not specified for endpoints which accept a gender parameter, records for total, male and female will be returned.

The function returns a tibble with each row representing a town in a particular year for a particular gender, and columns representing the variables returned by the API endpoint. If any API call returns no data, the values will be NA but the row will be returned. However, if all data_types do not return data for that town and year, no row will be returned for it.

    # example: returns output with no NA
    get_pop_queries(token, c("getReligion", "getLanguageLiterate"),
                    c("Bedok", "Yishun"), "2010")

    # example: returns output with no NA and gender field
    get_pop_queries(token, c("getEconomicStatus", "getEthnicGroup"),
                    "Yishun", "2010", "female")

If the data types request contains a mix of those that accept gender parameters and those that do not, only `gender = "Total"` rows will display all records. The data types that do not accept gender params will return results under `gender = Total`.

    # example: gender not specified
    get_pop_queries(token, c("getEconomicStatus", "getOccupation", "getLanguageLiterate"),
                    "Bedok", "2010")

    # example: gender specified
    get_pop_queries(token, c("getEconomicStatus", "getOccupation", "getLanguageLiterate"),
                    "Bedok", "2010", gender = "female")

If all data_types do not return data for that town and year, no row will be returned. A warning message will show data_type/town/year/gender for which an error occurred.

    # example: no records for 2012
    get_pop_queries(token, c("getEconomicStatus", "getOccupation"),
                    "Bedok", c("2010", "2012"))

Finally, to allow for faster computation, API calls can be called in parallel using `parallel = TRUE`. This is recommended for large requests.

## Route Service

These functions are a wrapper for the Route Service API. The Route Service API provides users a way to query the route taken from one point to another. It provides information about the total time and distance taken for the route, route instructions and other infomation e.g. elevation, for a variety of routes (public transport, drive, walk, cycle). This package provides two different functions associated with this API, each serving different purposes.

### Total time and distance matrix

The function `get_summ_route()` returns the total time, distance and optionally the route geometry between two points. Users input a vector of start coordinates and a vector of end coordinates. The function returns a tibble with `total_time`, `total_dist` and optionally `route_geometry`.

    # example: return driving distance and time between two points
    get_summ_route(token, c(1.320981, 103.844150), c(1.326762, 103.8559), "drive")

    # example: return public transport distance and time between two points, with route geometry
    get_summ_route(token, c(1.320981, 103.844150), c(1.326762, 103.8559),
         "drive", route_geom = TRUE)

If an error occurs, the function returns `NULL`, along with the API error message and status code.

    # example: returns NULL
    get_summ_route("invalid_token", c(1.320981, 103.844150), c(1.326762, 103.8559), "drive")

    get_summ_route(token, c(300, 300), c(400, 500), "cycle")

    get_summ_route(token, c(1.320981, 103.844150), c(1.326762, 103.8559), "fly")

### Total time and distance matrix

The function `get_travel()` allows the calculation of total travel time and distance for a tibble of start and end points. Users input a tibble of start and end points (and potentially other variables) and the function returns the tibble with additional columns, `total_time` and `total_dist`. Recognising that this API is most valuable for calculating total time travelled (as a improved measure of spatial distance compared to Euclidean distance), this function produces a cleaner output containing only the main variables of interest.

The function also accepts multiple arguments for `route` and `pt_mode`, allowing users to compare various route options.

Note that if `as_wide = TRUE` is selected, any columns with identical names as the additional output columns will be overwritten.

    # example: create sample df with start and end coordinates
    sample <- data.frame(start_lat = c(1.3746617, 1.3567797, 1.3361976, 500),
        start_lon = c(103.8366159, 103.9347695, 103.6957732, 501),
        end_lat = c(1.429443081, 1.380298287, 1.337586882, 601),
        end_lon = c(103.835005, 103.7452918, 103.6973215, 600),
        add_info = c("a", "b", "c", "d"))

    # example: multiple routes
    get_travel(token, sample[1:3, ],
        "start_lat", "start_lon", "end_lat", "end_lon",
        routes = c("cycle", "walk"))

    # example: multiple routes + multiple pt modes
    get_travel(token, sample[1:3, ],
        "start_lat", "start_lon", "end_lat", "end_lon",
        routes = c("drive", "pt"), pt_mode = c("bus", "transit"))

By default, the data appears in a wide format, but users can specify for the output to be in long format.

    # example: long format
    get_travel(token, sample[1:3, ],
        "start_lat", "start_lon", "end_lat", "end_lon",
        routes = c("walk", "pt"), pt_mode = c("bus", "transit"),
        as_wide = FALSE)

There is also the option to return a sf dataframe in long format by specifying `route_geom = TRUE`. This allows, for example, mapping of different route options.

    get_travel(token, sample[1:3, ],
        "start_lat", "start_lon", "end_lat", "end_lon",
        routes = c("drive", "pt"), pt_mode = c("bus", "transit"),
        as_wide = FALSE, route_geom = TRUE)

If an error occurs, the output row will be have NAs for the additional variables, along with a warning message. The warning message will show start/end/route/pt_mode for which an error occurred.

    # example: with error
    get_travel(token, sample,
        "start_lat", "start_lon", "end_lat", "end_lon",
        routes = c("cycle", "walk"))

Lastly, it recommended for users working with large matrices to set `parallel = TRUE` for more efficient computation.